/Engine/Plugins/Experimental/GeometryScripting/Source/GeometryScriptingCore/Public/GeometryScript/MeshMaterialFunctions.h
Compact the MaterialIDs of the TargetMesh, ie remove any un-used MaterialIDs and remap the remaining N in-use MaterialIDs to the range [0,N-1]. Optionally compute a Compacted list of Materials.
static [UDynamicMesh](API\Runtime\GeometryFramework\UDynamicMesh) * CompactMaterialIDs ( [UDynamicMesh](API\Runtime\GeometryFramework\UDynamicMesh) * TargetMesh, [TArray](API\Runtime\Core\Containers\TArray)< [UMaterialInterface](API\Runtime\Engine\Materials\UMaterialInterface) * > SourceMaterialList, [TArray](API\Runtime\Core\Containers\TArray)< [UMaterialInterface](API\Runtime\Engine\Materials\UMaterialInterface) * > & CompactedMaterialList, [UGeometryScriptDebug](API\Plugins\GeometryScriptingCore\GeometryScript\UGeometryScriptDebug) * Debug )